Wet bin for collection and quenching of ashes from a pulverized coal combustion chamber

ABSTRACT

A wet bin for collecting and quenching hot ashes discharged from an ash hopper of a pulverized coal combustion chamber includes an inclined table and scraper means which enables discharged hot ashes to be gradually quenched with increasing immersion in the water in the bin. This gradual quenching of larger lumps of hot ashes minimizes the possibility of explosive-like detonations that can accompany sudden and quick quenching. The wet bin may be sealed from the ash hopper by providing pivotally mounted flaps which extend beneath the water level in the collecting box of the wet bin to provide a barrier through which the scraper can pass without disturbing the seal since at least a pair of such flaps are provided at the sealed edge of the ash hopper discharge outlet.

ited States Patent 1 1 1 1 3,915,105

Michelbrink Oct. 28, 1975 WET BIN FOR COLLECTION AND 2,983,234 5/1961Reilly 110/165 QUENCHING OF ASHES FROM A 3,504,645 4/1970 Davenport110/165 3,771,470 11/1973 Hampton 110/171 PULVERIZED COAL COMBUSTIONCHAMBER [75] Inventor: Bernhard Michelbrink, Bislich,

Germany [73] Assignee: Deutsche Babcock & Wilcox Aktiengesellschaft,Oberhausen, Germany [22] Filed: May 7, 1974 [21] App]. No.: 467,713

[30] Foreign Application Priority Data May 22, 1973 Germany 2325923 [52]US. Cl. 110/165 1R; 110/171 [51] Int. Cl. F23J H00 [58] Field of SearchllO/8 R, 165 R, 171

[56] References Cited UNITED STATES PATENTS 2,589,836 3/1952 MartinllO/l65 Primary ExaminerKenneth W. Sprague Attorney, Agent, or Firm-Roland T. Bryan [5 7 ABSTRACT A wet bin for collecting and! quenching hotashes discharged from an ash hopper of a pulverized coal combustionchamber includes an inclined table and scraper means which enablesdischarged hot ashes to be gradually quenched with increasing immersionin the water in the bin. This gradual quenching of larger lumps of hotashes minimizes the possibility of explosive-like detonations that canaccompany sudden and quick quenching. The wet bin may be sealed from theash hopper by providing pivotally mounted flaps which extend beneath thewater level in the collecting box of the wet bin to provide a barrierthrough which the scraper can pass without disturbing the seal since atleast a pair of such flaps are provided at the sealed edge of the ashhopper discharge outlet.

6 Claims, 1 Drawing Figure US. Patent Oct. 28, 1975 WET BIN FORCOLLECTION AND QUENCHING OF ASHES FROM A PULVERIZED COAL COMBUSTIONCHAMBER BACKGROUND OF THE INVENTION This invention relates to a wet binfor collecting and quenching hot ashes discharged from an ash hopper ofa pulverized coal combustion chamber. In these wet bins, ashes which arestill hot inside are quenched by discharge into water in the bin. Whenlarge lumps of such ashes are introduced into the quenching water andsuddenly quenched, there frequently occur explosionlike detonations.

In German Pat. application No. P 02 670.813, there is disclosed a wetbin having a water-filled collecting box in which is located asupporting table positioned beneath the ash hopper outlet. This tablehas a grate-like structure provided with slots running in the directionof the movement of an endless scraper which moves over the upper surfaceof the table and removes hot ashes discharged there by scraping into thecollecting box. Such a wet bin has reduced the possibility ofexplosion-like detonations from sudden quenching of large lumps of stillhot ashes by providing a structure which shatters the ashes into smallpieces. These small pieces either drop through the slots in the tablegrate or cool off slowly in water which extends over the top of thesupporting table from which they are removed by the scraper into deeperwater in the collecting box.

When the water level is only slightly above the supporting table andbelow the bottom of the ash hopper, the wet bin is desirably sealed offfrom the ash hopper. This is essential to prevent the entry ofunfiltered air into the ash hopper, which is generally under a reducedpressure, which could undesirably have internal effects on the firing inthe combustion chamber. In the aforementioned German Pat. applicationNo. P 20 02 674.843, there is disclosed a wet bin which is sealed offfrom the ash hopper by means of a sealing body which floats on thesurface of the quenching water within the collecting box.

SUMMARY OF THE INVENTION The present invention is a further improvementon the above described wet bin and provides a wet bin which moreeffectively minimizes the possibility and hazard of explosion-likedetonations due to sudden quenching of large hot ash lumps. In addition,the present invention also provides an effective means of sealing thewet bin from the ash hopper in order to assure that no air enters theash hopper. The foregoing is accomplished according to this invention byproviding a supporting table which is inclined downward to thehorizontal surface of the water within the collecting box in thedirection of the movement of the scraper, so that hot ashes dischargedonto the table surface are gradually submerged in the quenching water asthey are removed therefrom. Thus, the supporting table slants downwardin the direction of the movement of the scraper moving along the uppersurface of the supporting table which is desirably positionedhorizontally in the area below the outlet of the ash hopper. The tableextends generally longitudinally and horizontally in the direction ofthe movement of the scraper while being inclined in a portion only, inthe region of its end from which the ashes are scraped into the deeperquenching water.

Thus, the larger ash lumps which are not sufficiently broken up on thesupporting table are slowly transported into the deep water on theinclined slope of the supporting table by the scraper means. The upperstringer of the endless scraper means passes along the upper surface ofthe supporting table to accomplish this. It has been found that thisslow but steadily increasing immersion of the large lumps results inthem being finally cooled off to the extent that after they havecompletely entered the quenching water in the collecting box, noexplosions or detonations occur. In this manner, damage to the wet binstructure and frame is avoided.

Therefore, it is an object of this invention to provide an improved wetbin that has a structure which quenches large hot ashes in a manner thatminimizes explosions or detonations and thus avoids damage to theframework.

The wet bin according to this invention also effectively seals off theash hopper from the wet bin collection box to assure that no air canenter it, This sealing is accomplished according to this invention by apair of flaps lying one behind the other in the direction of themovement of the scraper along the upper surface of the supporting table.These flaps may be situated on both sides of the ash hopper dischargeoutlet if necessary. The sealing flaps are pivotally separately hung onthe frame of the ash hopper on the corner of the wet bin so that thelower edge of each extends below the surface of the quenching waterwithin the collecting box. When the scraper passes through this barrier,the scraping element will lift one of the flaps at a time so that theother flap remains dipped into the water to effect the sealing off byitself.

Thus, it is a further object of this invention to provide a wet binwhich is effectively sealed from the ash hopper so as to prevent any airentering into the ash hopper during the operation of collecting andquenching the ashes discharged therefrom.

The above and further objects and advantages of this invention will beapparent from the drawing and the following description of an embodimentof a wet bin according to this invention.

BRIEF DESCRIPTION OF THE DRAWING The drawing diagrammaticallyillustrates, in crosssectional side view, an embodiment of a wet binaccording to this invention.

DESCRIPTION OF THE. PREFERRED EMBODIMENT Referring to the drawing, thereis shown a wet bin utilized to collect and quench hot ashes frompulverized coal combustion chambers of the type used in steam generatingboiler installations. In pulverized coal combustion chambers, the ashesappear dry and may be in powder, dust-like, granulated or sintered form.The ashes are discharged through the drop shaft of an ash hopper,indicated generally at l, and enter a collecting box 2 through thedischarge outlet of the ash hopper.

The collecting box 2 is essentially a trough open at the top whichinclines upward at one side. The collecting box 2 is filled withquenching water, up to the level indicated generally at 5, which is usedto cool the hot ashes. A scraper chain 6, to which the scrapers 7 areattached at a distance from each other along an endless stringer, runstraverse through the collecting box 2 in a direction of movement, of theupper stringer, indicated by the arrow 9. The scraper chain 6 is of theendless stringer type and is led around the rollers 8 to pass over theupper surface of a grate-like supporting table 11 and thence along thebottom of the collecting box 2. The ashes falling to the bottom of thecollecting box 2 are transported by the scrapers 7 of the lower stringerof the scraper chain 6 to the slag outlet and there dumped.

The lower end of the ash hopper 1 is moveably sealed off from thecollecting box 2 by means of an apron 3 which fits into a watercontainer 4 on the housing of the collecting box 2. Thus, the ash hopperl is moveably sealed off from the collecting box 2 through an effectivewater seal.

A supporting table 11 is provided below the outlet area of the ashhopper l at a slight distance below the surface of the quenching water.This table may be constructed as a plane surface grate having slotsbetween the bars of the grate which run in the direction of the movementof the scraper chain 6. In the embodiment shown, the supporting table 11is horizontal, and extends longitudinally in the direction of themovement of the upper stringer of the scraper chain 6, in the regionbelow the ash hopper outlet. A portion of the supporting table 11 beyondor downstream of the area of the ash hopper outlet (the direction shownby the arrow 9 being taken as progressing from upstream to downstream)is inclined downwardly to the horizontal surface of the water, indicatedat 5, within the collection box 2. This inclination is shown generallyat 11a.

The wet bin acts to quench the hot ashes as follows. Fine ash particlesdischarged from the ash hopper 1 arrive directly at the bottom of thecollecting box 2 by passing through the slots of the supporting table11. Larger lumps of ash break up on the bars of the supporting table 11and according to their size, either go through the table slots or arecarried along the upper surface of the supporting table by the scrapers7 of the scraper chain 6 which passes thereover. As the larger lumps ofash pass over the upper surface of the supporting table 1 1, those stillhot are cooled off slowly before they are discharged into the deeperwater within the collection box 2. This slow cooling is promoted by thefact that a portion of the supporting table is inclined, shown at 1 la,downward from the horizontal line of the water level. Thus, larger ashlumps are slowly but steadily dipped deeper and deeper into the water asthey pass along this downward incline. When the ashes fall on the bottomof the collecting box 2, they have been sufficiently cooled withgradually increasing contact with water so that the danger ofexplosion-like phenomenon occurring as a result of sudden contact of hotashes with water is greatly minimized.

Since the ash hopper 1 is under reduced pressure and because the waterlevel in the collecting box 2 is below the discharge outlet of the ashhopper, further special sealing is required. Thus, referring to thedrawing, two flaps 12 are provided one behind the other, in front orupstream of the ash hopper l, in the direction of movement of thescraper chain 6 as shown by the arrow 9. These flaps 12 are mountedalong the upper trough cover or on the ash hopper in such a way thatthey can pivot. As shown here, the trough cover is connected with thehousing of the ash hopper l. The lower edges of the flaps l2 dip intothe quenching water beneath the surface, shown at 5, to effect a seal.The flaps are mounted at right angles to the direction of movement ofthe scraper chain 6 and extend across the width of the collection box 2to provide the appropriate seal. Each flap 12 may consist of severalsections. When the scraper chain 6 passes through the flaps 12, thescraper 7 will lift one of the flaps 12, mounted one after the other,while not lifting the other. Thus, the flaps are mounted sufficientlyapart so that only one at a time can be lifted while one maintains aseal by extending beneath the water surface at all times. Thus, thedistance between the two flaps has a definite lowest value, whichdepends on the angle of deflection of the foremost flap and the distancebetween the scraper of the scraper chain, which should not be exceeded.As shown, a second pair of flaps 12 may also be located behind the ashhopper l in the event that the collecting box 2 is not closed at the topat this point.

Hence, there has been provided, according to this invention, an improvedwet bin for collecting and quenching hot ashes which minimizes thehazards of explosion and detonation associated with rapid quenching oflarge lumps of hot ashes and which provides an effective and improvedsealing means for maintaining the ash hopper sealed off from the wet bincollecting box.

I claim:

1. A wet bin for collecting and quenching hot ashes discharged from anash hopper of a pulverized coal combustion chamber comprising acollecting box situated beneath the ash hopper, the collecting box beingcapable of holding water, a supporting table means located within thecollecting box and beneath the ash hopper outlet to receive the hotashes discharged therefrom, an endless scraper means arranged to moveover the supporting table means and remove ashes from the upper surfacethereof into the collecting box, the supporting table means uppersurface being inclined downward to the horizontal surface of waterwithin the collection box, in the direction of movement of the scrapermeans along the upper surface, so that ashes removed from the supportingtable upper surface are gradually increasingly quenched by water withinthe collecting box.

2. A wet bin as claimed in claim 1, wherein the supporting table meansupper surface is horizontal in the area beneath the ash hopper dischargeoutlet and inclined downward only in portion, the inclined portion beingthat from which the ashes are removed into the collecting box from thesupporting table means upper surface.

3. A wet bin as claimed in claim 1, wherein the supporting table meansis grate-like with slots running in the direction of movement of thescraper means along the upper surface.

4. A wet bin as claimed in claim 1 wherein the collecting box is sealedfrom the ash hopper, with the exception of the ash hopper dischargeoutlet communicating with the area above the supporting table meanswhich receives the hot ashes, further comprising at least a pair ofsealing flaps pivotally supported on both sides of the ash hopperdischarge outlet, the sealing flaps being mounted one behind the otherin the direction of movement of the scraper means along the uppersurface and extending beneath the surface of the water in the collectingbox, the sealing flaps extending across the width of the collecting boxso that a vapor seal between the collecting box and the ash hopper isobtained.

5. A wet bin as claimed in claim 4 wherein the sealing flaps are mountedso that the'distance between each of 5 a pair, taken in the direction ofmovement of the scraper means along the upper surface, is such thatflaps are comprised of several sections.

1. A WET BIN FOR COLLECTING AND QUENCHING HOT ASHES DISCHARGED FROM ANASH HOPPER OF A PULVERIZED COAL COMBUSTION CHAMBER COMPRISING ACOLLECTING BOX SITUATED BENEATH THE ASH HOPPER, THE COLLECTING BOX BEINGCAPABLE OF HOLDING WATER, A SUPPORTING TABLE MEANS LOCATED WITHIN THECOLLECTING BOX AND BENEATH THE ASH HOPPER OUTLET TO RECEIVE THE HOTASHES DISCHARGED THEREFROM, AN ENDLESS SCRAPER MEANS ARRANGED TO MOVEOER THE SUPPORTING TABLE MEANS AND REMOVE ASHES FROM THE UPPER SURFACETHEREOF INTO THE COLLECTING BOX, THE SUPPORTING TABLE MEANS UPPERSURFACE BEING INCLINED DOWNWARAD TO THE HORIZONTAL SURFACE OF WATERWITHIN THE COLLECTING BOX, IN THE
 2. A wet bin as claimed in claim 1,wherein the supporting table means upper surface is horizontal in thearea beneath the ash hopper discharge outlet and inclined downward onlyin portion, the inclined portion being that from which the ashes areremoved into the collecting box from the supporting table means uppersurface.
 3. A wet bin as claimed in claim 1, wherein the supportingtable means is grate-like with slots running in the direction ofmovement of the scraper means along the upper surface.
 4. A wet bin asclaimed in claim 1 wherein the collecting box is sealed from the ashhopper, with the exception of the ash hopper discharge outletcommunicating with the area above the supporting table means whichreceives the hot ashes, further comprising at least a pair of sealingflaps pivotally supported on both sides of the ash hopper dischargeoutlet, the sealing flaps being mounted one behind the other in thedirection of movement of the scraper means along the upper surface andextending beneath the surface of the water in the collecting box, thesealing flaps extending across the width of the collecting box so that avapor seal between the collecting box and the ash hopper is obtained. 5.A wet bin as claimed in claim 4 wherein the sealing flaps are mounted sothat the distance between each of a pair, taken in the direction ofmovement of the scraper means along the upper surface, is such that whenthe scraper means passes a flap and pivots it only one flap of a pair islifted at one time in order to retain the seal.
 6. A wet bin as claimedin claim 5 wherein the sealing flaps are comprised of several sections.